Studies of the mechanism(s) by which varicella-zoster virus (VZV) becomes latent and is subsequently reactived have been hampered by the lack of an animal model or an in vitro system of latency. Recombinant DA technology, however, has how made it possible to study molecular aspects of VZV latency in human sensory ganglia. Utilizing this technology helped to establish the sensory ganglion neuron as the primary sight of VZV latency but the physical state of the VZV genome during latency remains unknown. Since recent studies on latent herpes simplex virus (HSV) infections have revealed limited gene expression from different gene classes, the expression of VZV genes will be analyzed both in vitro and in vivo. This project will study the expression of VZV genes from the immediate early, early and late regions. Selected genes from the immediate early, early and late VZV regions will be cloned into an in vitro transcription system, and be used to probe for gene expression from these regions by in situ hybridization. The above approach will be used first on VZV- infected cells in vitro, and then applied to normal human sensory ganglia and to sensory ganglia from humans with recent VZV infection. Our laboratory has cloned and mapped the complete VZV genome from which probes were made to detect VZV-DNA in ganglia. The in vitro transcription-translation system was developed in this laboratory and used for other studies of VZV gene expression. In this project I proposed to (1) clone specific VZV genes into in vivo transcription vectors; (2) identify the expression of these genes in infected cells; and (3) analyze by in situ hybridzation viral gene expression in human sensory ganglia. Accomplishing the aims of this proejct will yeild important information on VZV gene expression and function in normal and diseased human sensory ganglia.